Facts on Forests and Forestry

4. What is driving these losses in forest cover?

To prevent definition-based disagreements about the extent of deforestation, the term ‘deforestation’ is used here to mean a permanent change from tree cover to some other form of land use.

4.1. What are the natural causes of forest cover loss?
4.2. How is forest cover affected by human activities?
4.3. What are some indirect factors causing deforestation?

The extent of forest cover is increasing in the northern hemisphere mainly because of plantations or regenerated forests. However, ‘old growth forest’, which has more diversity and ecological functions, is declining because of continued logging. Some argue that this logging is a form of deforestation; others argue that it does not lead to permanent loss of forest vegetation and does not therefore constitute deforestation. More...

4.1. What are the natural causes of forest cover loss?

There are both direct and indirect causes of forest cover loss. Some are the result of human activity, some are the result of natural phenomena.

4.1.1. Windstorms can destroy significant areas of forests. In 1987, a severe windstorm in the United Kingdom destroyed some 160 km² of forest. In 1999, another storm destroyed some 5,000 km² of forests in France. More...

4.1.2. During the 20th century, diseases like the Chestnut blight or the Dutch Elm have affected US and European forests respectively. These diseases may irreversibly affect the species composition of forests but not their extent, because of natural regeneration. More...

4.1.3. Natural fires set off by lightning and dry conditions can cause forest loss. Many forest ecosystems have adapted to fire with, for instance, thicker barks and seeds which germinate in the ash on the forest floor after fires. More...

4.2. How is forest cover affected by human activities?

Some major direct and indirect threats to forests can be identified but often multiple factors combine to cause greater harm. In the case of tropical forests, deforestation has many complex causes linked in particular to land use changes. More...

The most significant human-related, direct causes affecting forest cover are listed below.

4.2.1. Conversion of forest land to agricultural uses

Humans have always cleared land for agriculture either for subsistence or for larger scale settling and planting.. The FAO claims that former is less a threat to forests than the latter. In developing countries, forestland is cleared under the traditional system known as ‘swidden,’ or ‘slash and burn’. Though blamed for deforestation, ‘swidden’ cultivation is actually quite sustainable, while clearance by migrants usually has greater long-term impact. Agricultural development programs initiated by governments, such as economic plans and resettlements in Indonesia, can also have substantial impact on forests. In the 1980s, US fast food companies were blamed for some deforestation in Central and South America caused by conversion to beef production. This practice is less profitable today due to more stringent legislation. More...

4.2.2. Conversion due to infrastructure development

The conversion of forestland to infrastructure development can take several forms, including road-building, hydroelectric dam construction, and mining. Road construction reduces forest cover both directly by occupying land, and indirectly, by fragmenting the landscape and opening it up for exploitation. A study showed that 86% of Amazonian forests lost between 1991 and 1996 were within 25 km of major roads. A similar process has occurred in Indonesia and Central Africa. Dam construction is an infrastructure development mostly affecting forests in Southeast and East Asia. Dams flood large populated areas, forcing migration or resettlement to more environmentally sensitive areas. This is turn leads to deforestation, degradation of forests and increased erosion. Mining can also impact forested areas usually immediately adjacent to the mine. Examples include the discovery of minerals and especially gold in the Brazilian Amazon and the mining carried out by large international corporations in Irian Jaya (Indonesia). More...

4.2.3. Harvesting forests for timber

Harvesting is an important factor in the global loss of forest cover but it often causes degradation rather than deforestation, as old growth is replaced with younger ecosystems or fewer species, or as areas are only partially logged. The extent of forest cover is most threatened when farmers, ranchers and fuelwood collectors move in to clear the land for other economic uses after harvesting is complete. According to the FAO (FRA 2000), timber harvesting takes place on some 110,000 km² of tropical forests each year. More...

4.2.4. Harvesting forests for pulp and paper production

Paper manufacture accounts for some 14% of the total world wood harvest. Most of the fibre used for pulp comes from managed temperate forests (only 2% from natural hardwood or tropical forests). The IIED in their study on “The Sustainable Paper Cycle” found that the sources of wood fibre mainly originate from managed natural regeneration forests (37%), plantations (29%) and thirdly from unmanaged natural regeneration forests (17%). Original conifer forest account for 15% while tropical rainforests and hardwood forests account for only 2% of the global wood pulp. Europe, North America and Japan are increasingly using recycled paper as a source of fibre. Sometimes, inappropriate pricing of forest resources and credit policies can lead to unsustainable investments in pulp and paper mills. In Indonesia, for example, an overcapacity of paper mills led companies to turn to natural forests after exhausting plantations. More...

4.2.5. Cutting of trees for fuel-wood and charcoal

Wood and charcoal are still the main source of energy for most people in developing countries. Cutting trees for fuel has visible impacts on forests, particularly near urban areas, but most analysts now believe that this is not a major cause of deforestation. While woodcutting for fuel does affect forest cover (especially near urban areas), it is more of a social problem—in which affordable supplies of fuel in urban areas are running out—than a global deforestation problem. The wood energy research for the last twenty-five years has reached the following consensual conclusions:

1. Wood and charcoal are vital sources of energy in developing countries.
2. Urban use of wood fuel places the heaviest pressure on forest resources.
3. The main source for wood and charcoal are dry tropical woodlands.
4. Programs to popularize ‘fuel efficient stoves’ have had a very modest impact.
5. Programs to promote the planting of fuel in woodlots, and improved charcoal burning technologies may ease the scarcity of wood fuel. More...

4.2.6. Acid rain and atmospheric pollutants

The most common form of atmospheric pollution believed to affect forests is ‘acid rain,’ defined as precipitation containing high levels of sulfuric or nitric acid. Acid rain and air pollution degrade forest vegetation. Damage varies with tree species and soil composition. Research in Eastern Europe, where in the past severe atmospheric pollution took place, is clarifying the links between this pollution and forest vegetation. Forests seem to recover well from mild pollution damage but more slowly with severe damage. Research on forest recovery is under way in an area of the Czech republic where 50% of the forest died in 1989 due to atmospheric pollution. On the other hand, there is evidence that carbon dioxide in the atmosphere increases the growth rate of forests. Radiation is another form of pollution. According to the University of Voronezh in Russia, 70,000 km² of forest in Russia, Belarus and Ukraine were degraded by the nuclear accident in Chernobyl. More...

4.2.7. Loss of forests to fire

Human activities can start fires deliberately or accidentally. These accidents can be caused by careless use of fire for the clearing of land or other purposes. They can burn out of control for long periods of time. Burned areas can recover but they are vulnerable because fires open up large areas of forest and the ash increases the fertility of the soil, thereby giving an incentive to agricultural use. Areas of concern include the Mediterranean forests, tropical forests and boreal forests in northern China and Siberia.
A prominent example of deforestation by fire is the case in1997-1998 in Sumatra and Borneo (Indonesia). Although there was wide disagreement at first, the final consensus is that 20,000 km² of land had burned, only some of it being forest. Indigenous people and smallholder farmers were accused of setting off the fires with their ‘slash and burn’ techniques. In fact, dry conditions caused by El Nino combined with a number of social, economic and policy factors to create the disaster. More...

4.2.8. Destruction of forests in the course of warfare

Warfare can lead to long-lasting deforestation. Forest fires can be set off in a battle, deliberately or not. The Vietnam War can be cited, but also conflicts in Myanmar (Burma) and Sri Lanka. More...

4.3. What are some indirect factors causing deforestation?

4.3.1. Impact from population pressure

Population pressure is known as the main cause of deforestation, but sometimes increases in population occur at the same time as increases in forest area. The outcome of an increased population density depends on economic opportunities, agricultural systems and access to timber and other markets. Population growth due to migration into forested areas has had rather adverse effects in terms of deforestation (e.g. the Amazon) whereas evidence exists of increases in local populations being paralleled by increases in the forested area (Europe, North America and Kenya). More...

4.3.2. Link with poverty

Poor people in rural areas may be forced to open new land to produce more food, prioritizing short-term survival over the long-term sustainability of forests. However, the link with poverty is difficult to quantify. More...

4.3.3.Relationship between land tenure systems and forest clearance

In many countries, the law and land ownership systems make it easy to take over ‘unutilized’ forest land. If demonstrating use of public land leads to its ownership, then there is an incentive to clear a forest. Insecure land tenure systems are a further disincentive. More...

4.3.4. Perverse incentives of some economic policies

Some economic policies give perverse incentives to clear forest land rather than to conserve forest land. Examples include the underpricing of forest resources and government subsidies to expand agriculture and establish plantations of cash crops. More...

4.3.5. Conversion of forests for expansion of cash crops production in developing countries

Many developing countries have large debts requiring foreign ‘hard’ currency to pay the interest. The incentive is then to convert forests to expand the production of export crops such as palm oil, rubber or coffee. Sometimes economic policies, such as Structural Adjustment Policies (SAPs) that are meant to address economic crises, may encourage faster exploitation of resources such as forests and fisheries. In many cases, economic policies are followed but clauses calling for the protection of natural resources are ignored. More...

4.3.6. Poor governance and flouted forest conservation policies

Poor governance and corruption are making it easy to flout policies and legislation aimed at forest conservation and protection. As international agencies pay more attention to good governance, transparency and accountability, there is growing recognition that corruption facilitates illegal deforestation and that a significant proportion of deforestation occurs illegally despite laws designed to protect forests. More...